#include <iostream>
#include<string>
using namespace std;


int cut(string& s, string& t){
    int ret = 0;
    while(s.find(t)!=string::npos)
    {
        s.erase(s.find(t), t.size());
        ++ret;
    }
    return ret;
}

void Test1(){
    string s, t;
    while(cin>>s>>t){
        int ret = cut(s, t);
        cout<<ret<<endl;
    }
}


void Test2(){
    long long arr[80];
    arr[0] = 1;
    arr[1] = 1;
    for(int i = 2; i < 80; ++i)
        arr[i] = arr[i-1]+arr[i-2];
    int from, to;
    while(cin>>from>>to){
        long long ret = 0;
        for(int i = from-1; i <= to-1; ++i)
            ret += arr[i];
        cout<<ret<<endl;
    }
}

int main() {
    Test2();
    return 0;
}
